Sweeper mechanism for heat exchanger



March 2, 1965 A G. BAUER SWEEPER MECHANISM FOR HEAT EXCHANGER Filed March 26, 1962 Sheets-Sheet 1 March z, 196s Filed March 26, 1962 A G. BAUER SWEEPER MECHANISM FOR HEAT EXCHANGER 2 Sheets-Sheet 2 United States Patent O 3,171,472 SWEEPER MECHANSM FUR HEAT EXCHANGER Arthur G. Bauer, 90 Allen Blvd., Farmingdale, N.Y. Filed Mar. 26, 1962, Ser. No. 182,406 s claims. (ci. 16s- 12) This invention relates to a device and method for cleaning heat exchanger tubes yfree from soot and more particularly to such heat exchanger attached to the exit flue of oil burners used in the heating of homes.

The oil burners conventionally used to heat homes are generally very wasteful and ineiiicient in that a vast amount of hot air is blown up the chimney and into the atmosphere by the burner fan used to supply air to the combustion chamber.

In this invention a heat exchanger is disposed in the exit flue, having a plurality of heat exchanger tubes disposed at a right angle to the exit iiue and the flow of the combustion gases therein.

Thus, for example, the temperature of the gases coming into the heat exchanger located in the exit flue adjacent to the furnace may have a temperature of about 650 F. whereas the combustion gases leaving the heat exchanger may have a temperature of only about 250 F. Thus there is a large drop in temperature of the flue gases in passing over the plurality of tubes in the heat exchanger, the heat being directed into the cellar of the home or conducted by conventional air ducts where desired.

A disadvantage of using heat exchanger in the exit iiue is that soot condenses on the heat exchanger tubes and builds up with time so as to seriously interfere with the flow of the combustion gases from the furnace into the chimney, and said soot being a heat insulator seriously affects the eliiciency of the heat exchanger.

Accord-ing to this invention, mea-ns are provided for cleaning the heat exchanger tubes whenever the furnace is in operation. The heat exchanger while described in conjunction with a home oil burner is not limited to oil fired furnaces nor to home use, since clearly it is operable for larger installations as well.

Also according to this invention means are provided for turning off the furnace oil burner should the sweeper mechanism or its co-acting electric clock fail. This is important, for as stated above, if the furnace operates without operation of the cleaning means in the heat exchanger, the soot will build up and interfere with the flow of the gases of combustion and furthermore, the soot greatly interferes with the transfer of heat since it functions as an insulator. ln extreme cases, a heavy soot buildup is equivalent to a total insulation of the heat exchanger tubes.

This invention provides means and method for continuously keeping the heat exchanger tubes clean and it also provides a means and method -for shutting off the furnace should the actuating means for the sweeper or electric clock used in conjunction with the sweeper fail.

This invention is described by a plurality of embodiments shown in the accompanying drawing but is not limited thereto.

FIG. 1 is a longitudinal view through a rectangular heat exchanger `disposed transversely in the round flue pipe from the furnace and showing a few of a large plurality of heat exchanger tubes and the sweeper means and the actuating means for operating said sweeper means,

FIG. 2 is a front elevation view of one embodiment of safety switch means used in conjunction with the operation of the sweeper plate,

FIG. 3 is a front elevation of a modified safety switch,

FIG. 4 is a front elevation of another modified safety switch,

ICC

FIG. 5 is a schematic elevation View of a clock wheel and wheel riding switch means, said wheel being provided with a first rim notch for turning olf the furnace main switch in the event of 'failure of the sweeper means and provided with a second rim notch for turning olf the furnace main switch in the event of clock failure,

FIG. 6 is a schematic wiring diagram of this invention,

FIG. 7 is a view taken substantially on line 7-7 of FIG. l showing a fixed cam and a free wheeling cam disposed on the clock shaft,

FIG. 8 is an exploded view of the sweeper plate showing its laminate structure and the means of captively retaining a pair of floating cleaner rings, and

FIG. 9 is a section view of the pawl means used to advance and to return the sweeper plate.

Turning to the drawing, a rectangular shell 10, preferably of rust resistant or stainless steel, is provided with a conventionally secured end plate 11 having an aperture 12. therein to which a blower pipe 13 is attached. The blower pipe 13 leads to a conventional electric motor operated blower (not shown). The top wall of the shell 10 is provided with a longitudinal slot 14 for a pair of cams, to be described hereinafter, and also with a substantially square slot 15 through which a sprocket chain 16 is passed.

The opposed side walls of the shell 10 are each provided with suitably large aperture 17 to which the flue pipe is attached.

A heat exchanger unit 18 preferably of stainless steel is provided with a multi-apertured rectangular inner wall 19 having a peripheral exteriorly disposed continuous edge 20 at a right angle thereto. The interior walls of the chamber of shell 10 is provided with a substantially continuous holding strap 21 secured at one end as by welding to the shell. As shown in FIG. l, the continuous edge 20 lockingly and substantially hermetically engages the strap.

The exterior heat exchanger wall 22 is of slightly larger height and width and is provided with a continuous lip 23 to overlap the adjacent edge of the shell 1t), said lip being removably secured to the shell by conventional means such as screws.

The exterior plate Z2 has a like manner of apertures disposed in corresponding relationship to inner plate 19. A plurality of heat exchanger tubes 24 are disposed between the end plates 22 and 19 and are crimped thereto by hydraulic pressure to effect an air tight seal.

A central shaft aperture is provided in each plate 19 and 22 and a conventional re-entrant spiral shaft 25 is disposed in these apertures. Preferably a suitable apertured bearing plate 26 is secured as by welding, bolting or riveting about each central aperture in each end plate to provide a suitably large bearing surface.

As shown in FIG. l, the shell 10 is -provided with an end chamber between shell end plate 11 and the inner heat exchanger end plate 19. The end of shaft 25 protrudes into this chamber and it is provided with a conventional sprocket wheel 27. The chain 16 engages wheel 27 and is connected to the shaft of a suitable motor 28, which latter lis secured by metal bolts to the top wall of the shell or housing 10, or by slotted adjustable angle fitting (not shown) The shaft 25 is provided with a continuous re-entrant spiral groove 29 so that a pawl `follower 30 having a tongue disposed in the groove will travel continually back and forth along the shaft 25 upon turning of said shaft.

An important feature of this invention is the provision of a unique sweeper plate 31. The plate 31, as shown in FIG 8 is of a laminate construction consisting of a thin inner perforated sheet 32, a middle relatively thick perforated sheet 33 and a thin outer perforated sheet 34.

3 The number and location of the perforations correspond to the number and location of the heat exchanger tubes 24. The perforations of sheets 32 and 34 are round and slightly larger than the diameter ofthe tubesY 2,4, whereas the round perforations of the middle sheet 33 are considerably largery thanrthe diameter of the tubes 2,4.

A, Pair f' like. diameter. thin flat rings 3.5 is disposedV Witt-1in wh 0f` the apertures 36,- 'Tfhe'fisS 35. having an outer diameter suitably less` than the diameter of aperture 36, and said rings have'an outer diameter suitably greater than the outside diameter of the apertures 3 7 of sheets 32 andr 4, and an inner diameter having a free sliding fitV over tubes 24. Y

Accordingly rings It are captively, and. loatingly heldin between sheets, 3,2' and 34. within aperture 36 ofthe middle sheet 3??. Clearly as the rings V35: gravitationally` are rnovingly pushed` over the tubes 24 they have a scrubbing action on the tubes,(therc-by` removing any soot clinging thereto, which removed soot is. then blown away up the Chmasyf As shown in FIG. 1, a. container 38 having a chamber to receive the pawl followert), is secured to the laminate sweeper. plate 31 by a pair of screws 39. so that it can not be rotated and therefore isfin effect: integral with said laminate plate 31'. Thepiate 31 can notrotateV sinceit is capitively held by the tubes v2 4 passing therethrough, the.

number of tubes24. being for example, aboutthirty two. f

Aco'ver plate`40 is secured to the top of the container 3 8,l to keep the pawlr followenin place and forI removing said followed if necessary; A tab'41 is secured,'as by spot welding, to the top of the laminate platefgltv A safety feature ofv this. invention is. tlieprovision of means, turning offthe.i entire unit includingtheoilY burner.A if the 'operating` or sweeper mechanism, shouldfail. `VPlio accomplishthisresult a conventional electric clock mech.-V

anisrn 4,2.is employed. 'The shaft 43; ofY theclock Iisoprovided withf a' conventional slip clutch (not shown). AsY shown in FIG. 5,4 a switch operating Iwheel 44p'referably of suitable plastic construction is secured to the. shaft 4 3, A conventional micro-switch element 45, 'shown schematically in FIIG. 5, is provided. with a switch, contact. leg46` Y and a friction. contact log4j. "The Contact leg rides onV the rim surfacev offthe .wheel 44, normally betweentwo depressions. or cut-outs 48.-and, 42` locatedfsuitably in4 saidv rim surface. l'

Turning to the wirnadiagram ELG- 6.. th.e -en rsi2.d; 0r hot electricalV wire 5,01 fro'mthe, stach. control enters the` micro-switch unit, shown in dotted outline, where con-v tactbetween wires Sland 5,2 is madednring'norrnah con; tinuous operation'. When however the sweeperV unit or the clock unit failsthe wheel; 4,4 isrotated sothat leg, 47

4 is disposed. The freeV inner or. wheeling cam. 61 is proa vided with a bushing 64, lwhich is not secured to shaft 43. Shaft 43 is preferably provided with a flat area 65, against which set screw 63 isrigidly secured.

The outer Cam 69 strovided With a Suitable rim fab 66 and the inner cam with a suitably contigui-ated rim tab'67. Cam'60 is providedwith an integral handle portion 68 havingan integral tongue 659 at right angle thereto. The inner cam 61 is also provided with an integral handle lportion 70 having a suitable integraltongue 71at'a right angle thereto. A tension spring! 72 issecured to the ton-'- gues 69 and 71tending to pullv them together. As shownY in FIG. .2, a suitable arresting flap 733.V is turned over at arishtangletotheplane'ofeam 6.1. f y In the operation of.` the 6,0 andy 61,'FIG. 1*,- the sweeper plate 1,3 isy moved by motorZS, during the oil burning operation only, slowly haelt and. forth on, for. example, a twenty four minute cycle. o

The clock mechanism t2l rotates the fixed. camu@ and the,` arrested free wheeling carri counterclockwise at a suitable number of degrees per minute.

Thus the free wheeling camolyis'arrested in its clock.-y

wise rotation butv isf-ree wheeling ina counterclockwise falls into a depression 4,8or 42 as tlztecase` maybe, there# Y by moving leg 46 so as'to effect a Contact between wires 5,3 and 54which are openfin normal; operation.

As shown inthe wiring diagramFlGfzandFG- 54th? wire 52 of the normally, closed contact` energizes they sweepermotor 2 8. and the clock motorrrSpS in the clock unit 4 2 as' well as theoil-burnerrmotor 5.6, the return line or ground wire being indicated. by the number. 57.

Whenever the leg47 falls in to a depression 48.'` or` 49, the normallyopen switchis closed andthe normally closedy switch is opened SQ that the Sweeper, IIJLQtQrl Sitheciot motor 5S.v and the oilfburnsr. motor 5.62116., turned Off s irll nowl the current. owsthrotlglt Wires; 5i?? 5?, l54 and the pilot light 58 and thence through wire 5'9 ..toithe groundwire 57;-(EIG. 6).' Y y Various meansmaybe provided forZ actuatingthe clock wheel, a plurality ofrthree embodiments being shown in FIGS; 2,'3vand 4.

Turning to FIGS. 2 and 7, Va pair of. segment cams are provided, namely an outer or tixedcarn 6 ,0fand an inner, or free wheeling cam 6 1. Cam 60,'isprovided with a 43 and a threaded radial aperture in'which a set screw 63 g this condition, the location of the. dependinglefg-47of the microswitch is shown in EI'G, 5f and is betweenthe notches or depression 4Sv and 49. In normal'operation, leg 4 7 always rides on the/wheelrimbetweenrthese twonotches.

It is only when something goes .wrong that the terminus4V ofithe leg 47-Ufall'sy into a notch to actuate or close the normally onenswtch andtlareby. sans?, theo-,lot lisht t@Y light up indicatingtrouble in .the operation,

The. Sweeper. plata 3.1. iS. moved t@ th, fight by mil-ationof theshaft 2,5; and the cani follower 36.V `Iri'srndoing the tab 41 contacts and rnovestab 67 andfthus suitably countercloclgwise rotates, inner Cain vHowever cam 6 1 is` spring loadedto fixed earn 6), and. it is .moved.counterclockwisey faster than the vfixed. 'outer barn. 60. l'lctv? counterclockwisedue to` clock rotationuntil 67 snaps. back over the pushing tabz 41`on,the". sweeper. plate, to be. to the left of the tab 41. rlfhe sweeper plate 18'. and its tab 41o-then continues totheeittrernefright (FG', 1 and then returnsI leftwardly. Meanwhile theclocl has rotated. both cam 6,0 andthe arrestedcam 61 so that. on the return Of; the sweeper plate, tabf41v clears tab'67., of the innerr cam 6:1 and: engages. cam 6,6.of ythe outerV cam arid puSheS it leftwardly against the slip Aclutch of the clock unit- 4 2 to return bothl cams to. their leftwardfrnost position; a5.. shown inlFIlCt. 1, whereupon'the cycle is repeated.

IfIOWeverk should the. sweeper; platel fail: to Operate fo.

EtIlYJeason` as forexarnple, a broken chain 16, the sweeper actuator tab 41 will not recycle the clocl. timer.

Shaft' 43 thereby Shutingzcffthe .Oil Burner, Sweeper. motor,

andclock motor and lightinguptheswarningr. light v58.v

In case theclock should-VfaiLthesweeperplate makes onev normal; cycle and since the earns 6.0 and 611,1"1ave`not` rotated due to the cloclg'failure, thel actuator tab 41 von the sweeper plate on its return leftward trip;engagesv the outer surface of. tab 6'7 -of cam 61. and pushes cam'6.Q,by Way of theV arrester flap 73until leg4l7 drops into suitably located notchv48, thus: again turningotfthe 'sweeper motor,`

burner ymotor andl lighting up therwar'ning light 58.

A pair of'modied cams are shown in FIG.V 3f In this l Y modification caml 60 has aV modifiedintegral handle 63X hiv/inge projection VStltab .in'theV plane of the/carn. The projection Stl'eng'ages the upright tonguell of thehandle 70 of cam 61. In the moditica'tion of FIG.k 3, the Hap 73 on cam 61v is deleted and the projection Siton the cam 60 handle 68X is substitutedin lieu thereof;

Another modification is shown in FIG. 4. Inthis modiiff ication, the arresting flap 73 on inner cam 61 is deleted. The cam 60 is provided with a suitable curved slot 81 and a fixed pin 82 is secured to cam 61 and protrudes through the slot and is adapted to move in said slot S1. A pin 83 is ixedly secured to the handle 6SY of the cam 30 and a suitable two prong spring 84 is disposed so as to be biased against pin 83 with one prong and against pin 82 with the other prong, said spring having a central loop 85 disposed about the bushing 62. The spring 84 and its coacting pins 82 and 83 with slot 81 substitute functionally for the spring '72 and flap 73 of the modification of FIG. 2.

This invention has been described by a plurality of embodiments but it is not limited thereto as it is of broad or generic scope.

I claim:

1. In a heat exchanger having a burner motor and a housing having a slot aperture in its top wall and disposed in a tiue pipe and having a plurality of parallel heat exchanger tubes disposed in the flue gases, a movable apertured sweeper plate engaging said tubes in the apertures thereof and disposed transversely to said tubes, a rotatable re-entrant spiral shaft engaging said plate and electrical motor means for rotating said shaft, the safety improvement for turning olf burner motor power in the event of mechanical failure comprising tab means secured to said sweeper plate and slip clutch electrical clock means secured to the outside top wall of said housin7 adjacent said slot aperture therein and disposed over said tab means, said clock means having an electrically operated rotatable shaft, a first disc means lixedly secured to said shaft and having a rim tab disposed in said housing slot aperture, a second disc means freely mounted on said shaft and having a rim tab disposed in said slot aperture, arresting means disposed on said second disc for engaging said lirst disc, spring means engaging said first and said second disc means urging continuous engagement of said arresting means, a rim dual notched wheel mounted on said shaft and electrical Contact means engaging selectively said notches to cut off power supply in the event of sweeper piate failure or electrical clock failure.

2. The device of claim 1 wherein the first disc means comprises a substantially semi-circular fiat portion having an opposed integral handle, said handle having an integral tongue element at about a right angle thereto, the rim tab thereof being substantially in the center of the semi-circular rim; the second disc means comprises a substantially semi-circular flat portion also having an opposed integral handle, said handle having a suitable integral tongue element at about a right angle thereto, the rim tab of said second disc means being substantially in the center of the rim thereof, said arresting means of the free second disc engaging the lirst disc to effect a spaced-apart relationship of said rim tabs, said spring means being a coil spring engaging the respective tongues of the respective handles of said disc means.

3. The device of claim 2 wherein the arresting means of said first disc is a turned over edge iiange adapted to engage an edge of said semi-circular portion of said second disc means.

4. The device of claim 2 wherein the arresting means is a planar projecting element of said handle of said lirst disc means adapted to engage said tongue of said second disc means.

5. The device of claim 1 wherein the spring means is a loop spring the loop of which is disposed about said shaft, said lirst disc being provided with an angular slot, said arresting means being a pin secured to said second disc and protruding through said slot, said loop spring being secured at one end to said first disc means and at the other end to said pin protruding through said slot.

References Cited in the tile of this patent UNITED STATES PATENTS 2,890,862 Heller June 16, 1959 FOREIGN PATENTS 529,306 Great Britain Nov. 19, 1940 

2. IN A HEAT EXCHANGER HAVING A BURNER MOTOR AND A HOUSING HAVING A SLOT APERTURE IN ITS TOP WALL AND DISPOSED IN A FLUE PIPE AND HAVING A PLURALITY OF PARALLEL HEAT EXCHANGER TUBES DISPOSED IN THE FLUE GASES, A MOVABLE APERTURED SWEEPER PLATE ENGAGING SAID TUBES IN THE APERTURES THEREOF AND DISPOSED TRANSVERSELY TO SAID TUBES, A ROTATABLE RE-ENTRANT SPIRAL SHAFT ENGAGING SAID PLATE AND ELECTRICAL MOTOR MEANS FOR ROTATING SAID SHAFT, THE SAFETY IMPROVEMENT FOR TURNING OFF BURNER MOTOR POWER IN THE EVENT OF MECHANICAL FAILURE COMPRISING TAB MEANS SECURED TO SAID SWEEPER PLATE AND SLIP CLUTCH ELECTRICAL CLOCK MEANS SECURED TO THE OUTSIDE TOP WALL OF SAID HOUSING ADJACENT SAID SLOT APERTURE THEREIN AND DISPOSED OVER SAID TAB MEANS, SAID CLOCK MEANS HAVING AN ELECTRICALLY OPERATED ROTATABLE SHAFT, A FIRST DISC MEANS FIXEDLY SECURED TO SAID SHAFT AND HAVING A RIM TAB DISPOSED IN SAID HOUSING SLOT APERTURE, A SECOND DISC MEANS FREELY MOUNTED ON SAID SHAFT AND HAVING A RIM TAB DISPOSED IN SAID SLOT APERTURE, ARRESTING MEANS DISPOSED ON SAID SECOND DISC FOR ENGAGING SAID FIRST DISC, SPRING MEANS ENGAGING SAID FIRST AND SAID SECOND DISC MEANS URGING CONTINUOUS ENGAGEMENT OF SAID ARRESTING MEANS, A RIM DUAL NOTCHED WHEEL MOUNTED ON SAID SHAFT AND ELECTRICAL CONTACT MEANS ENGAGING SELECTIVELY SAID NOTCHES TO CUT OFF POWER SUPPLY IN THE EVENT OF SWEEPER PLATE FAILTURE OR ELECTRICAL CLOCK FAILTURE. 